Coal-auger.



0'. R. ANDERSON.

. COAL AUGER. APPLIOATION FILED MAR. 29, 1909.

Patented Nov. 2, 1909;

CECIL B. ANDERSON, OF BELLEVUE, PENNSYLVANIA.

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Specification of Letters Patent.

Application filed March 29,1909.

Patented Nov. 2,1909.

Serial No. 486,367.

To all whom-it may concern:

Be it known that I, Groin R. ANDERSON, a resident of Bellevue, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Coal-Angers, of which the following is a specification.

Angers for drilling coal are formed by twisting rolled blanks or bars, and the usual practice is to provide the same with an integral bit. This bit is formed by bifurcating the end of the auger and forming cutting edges of the extremities of the bifurcated part. The bifurcation is formed by removing the central portion of the drill for a distance inward fromits extremity, the'recess tapering inwardly so that if the metal we're flattened out, i. 6., were not twisted, the recess would be V-shaped. As the bit wears off it is sharpened or renewed by extending the bifurcation, and this sharpor renewing process is repeated from to time as required until the anger is too short for further service.

in coal angers now generally used the metal is thickest at the longitudinal center thereof. and hence the extending inward of the bifurcation in the bit-sharpening or renewing process is a laborious operation; and furthermore, with the thickest part of the metal thus removed the bit is not as strong and durable as it should be. The present invention is designed to obviate these difficulties without detracting from the strength r ()1'-I,illilly of the auger by forming the metal thinner at the longitudinal center of the anger than-in those portions at opposite sides of the center which enter into the formation of the spiral convolutions. Hence, the removal of the metal in forming and re newre; the bit is less laborious than heretofore: and the thicker portions of the metal uito'the bit-forming wings, o the latter a very substanstiivnal are in the drawings, Figure 1 on of a coal auger thereon. Fig. 2 is 1 on lin 2-2 of Fi 1. Fig. ss-seetion of one of the hit-forming ken on line of Fig. 1. l of a portion. a blank from. ch L '3 twisted, and Fig. 5 is a cross section ereof.

Referring to the drawings, 2- designates the relatively thin longitudinal central portion of the auger, and 3 are the thicketpor-- tions at opposite sides of part 2 and which enter the convolutions of the twist. The outer longitudinal extremities of the thicker portions are reduced to provide the outer edges 4 of the twist.

Formed integral with the body of the anger is the bit or cutter element which consists of wings 5 separated by the incision 6, the extremities of the wings beingv sprung apart slightly so as to have a transverse area. slightly greater than the body of the auger. Incision 6 is formed by cutting away the relatively thin central portion 2, which is accomplished with less labor and less waste of material than in those forms of twisted angers wherein the thickest metal is at the the anger is twisted, is shown in Figs. 4 and 5'), the section of which illustrates rounded or convex longitudinal portions 8 on the opposite side faces of the blank and at op osite sides of the relatively thin longitudinal center thereof; each of the thicker or convex portions having an opposite fiat surface 9 which form the c'oncaves of the spirals when the auger is twisted. When a blank of this section is twisted, the flat faces 9 form the spiral concaves 9 which confine the borings within the auger, and operate as a conveyer to work them out of the hole, thus making the auger self-cleaning. Edges 4: rovide clearance for the auger even where t e hole isdrilied slightly crooked and prevent the auger from sticking, at such time the edges acting as cutters or scrapers. Also, sald' edges serve to gather the cuttings into the spiral concaves of the auger, as above indicated. With only edges 4; engaging the wall of the hole, there is less friction than would result if the exposed surfaces were flat or blunt.

I claim:--

-1. A- coal auger having thin edges merging into the thicker portions forming the wings or convolutions of the twist,*and such thicker metal being in turn thinned to form the longitudinal center of the auger.

2. A twisted coal anger in cross-section having a relatively thin central portion and thicker side portions forming the convolutions of the twist, the thicker side portions being of outwardly decreasing thickness and providing relatively thin outer edges, one face of the spiral extending from the center of the auger to the thin outer edge being 7 concave and the opposite face thereof extending to said edge being convex.

3. A twisted coal auger having the metal of its lon itudinal center thinner thanthe metal of tie twist at either side of the center and with the outer portions of such thicker parts thinned for the purpose described, the metal at one side of the centerviewing the auger in cross-section-having one face concave and the other face convex,

and the metal at the other side of the center having like concave and convex faces disposed reversely to the faces first mentioned.

i. A twisted coal auger having the metal ofits longitudinal center thinner than the metal of the twist at either side of the cen-- ter and with the outer portions of such thicker parts thinned for the purpose described, the metal at each side of the centerviewing the anger in cross section having a concave and a convex face, the extremity of the auger bifurcated to form an integral bit with said thicker portions -of-the metal extending into and forming part of the bit wings. r

' In testimony whereof I atfix my signature in presence of tWo witnesses.

CECIL R. ANDLRSONI Vitnesses:

ALEX. S. Mason, J. M. NESBIT. 

